Sökning: "chromium oxide"

Visar resultat 1 - 5 av 83 avhandlingar innehållade orden chromium oxide.

1. 1. Key Aspects of Sintering Powder Metallurgy Steel Prealloyed with Chromium and Manganese

   Författare :Ola Bergman; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Manganese; Prealloyed; Sintering; Mechanical properties; Chromium; Spinel oxide; Powder metallurgy; PM steel; Oxide reduction; Residual oxides; Atmosphere;

   Sammanfattning : The powder metallurgy (PM) process is a cost efficient near net-shape technology suitable for sustainable manufacturing of structural steel components. A drawback with the PM technology is the difficulty to use oxidation sensitive alloying elements, such as Cr and Mn. LÄS MER

3. 2. Measurements of the thermodynamic activities of chromium  and vanadium oxides in CaO-MgO-Al2O3-SiO2 slags

   Författare :Pengli Dong; Seshadri Seetharaman; Mselly Mbwambo Nzotta; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; thermodynamic activity; chromium oxide; vanadium oxide; equilibrium; slags; slag basicity; gas-equilibration technique; Metallurgical process engineering; Metallurgisk processteknik;

   Sammanfattning : In the present work, the thermodynamic activities of chromium and vanadium oxide in CaO-SiO2-MgO-Al2O3 slags were measured using gas-slag equilibration technique. The slag was equilibrated with a gas mixture of CO, CO2 and Ar gases enabling well-defined oxygen partial pressures in the gas mixture (PO2=10-3,10-4,10-5 Pa) at temperatures 1803, 1823K, 1873, 1923 K. LÄS MER

4. 3. Studies of oxide reduction and nitrogen uptake in sintering of chromium-alloyed steel powder

   Författare :Ola Bergman; John Ågren; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; powder metallurgy; chromium; pre-alloying; surface oxides; sintering; Materials science; Teknisk materialvetenskap;

   Sammanfattning : The powder metallurgy (PM) process route is very competitive for mass production of structural steel components with complex shape, due to efficient material utilisation, low energy consumption, and short overall production time. The most commonly used alloying elements are the processing friendly metals Cu, Ni and Mo. LÄS MER

5. 4. Critical Aspects of Delubrication and Sintering of Chromium-alloyed Powder Metallurgy Steels

   Författare :Seshendra Karamchedu; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; delubrication; oxide reduction; surface oxide; carbon control; sintering atmosphere; chromium-alloyed sintered steels;

   Sammanfattning : The cost efficiency and performance of Powder Metallurgy (PM) steels can be improved by replacing conventionally used alloying elements such as copper and nickel with chromium. Utilizing chromium imposes a challenge in terms of processing due to its effect on powder compressibility and high oxygen affinity, the latter of which, to a certain extent, is dealt with by introducing chromium in prealloyed form that decreases its activity. LÄS MER

7. 5. The rule of hydrogen and rare earth metals in the formation of protective metal-oxides

   Författare :Bent N. Tveten; KTH; []
   Nyckelord :chromium; high-temperature corrosion; oxide growth; scale adherence; hydrogen; yttria; REM; reactive element effect; gas phase analysis;

   Sammanfattning : The effects of hydrogen and rare earth metal (REM) additionson the oxidation behavior of metals and alloys that formchromia, alumina and zirconia in 20 mbar O2and/or H2O have been investigated at elevated temperatures.The metal-gas reactions were studied by the use of isotopicallylabeled gas in combination with mass spectrometry and bymeasuring changes in the total pressure in a closed reactionchamber. LÄS MER